- Why does an aqueous solution of acid conduct electricity?
- How does the concentration of hydrogen ions [H30+] changes when the solution of an acid is diluted with water?
- Which has higher pH. A concentrated or dilute solution of HCl?
- What would you observe on adding dil HCl acid to
(a) Sodium bicarbonate placed in a test tube.
(b) Zinc metal in a test tube.
An aqueous solution of an acid conducts electricity because in water, an acid (HCl) dissociates to give ions. Since, the current is carried out by the movement of ions, an aqueous solution of acid conducts electricity.
During dilution, more of acid dissociates into ions. Thus, concentration of [H3O]+ ions will increase on dilution.
Even on increasing [H3O]+ ions, the number of ions per unit volume decreases.
Therefore, pH will increase on dilution.
(a) CO2 gas will evolve accompanied by brisk effervescence.
NaHCO3 (s) + HCl (aq) → NaCl (aq) + CO2(g) + H2O(aq)
(b) H2 gas will evolve accompanied by brisk effervescence.
Zn(s) + 2HCl (aq) → ZnCl (aq) + H20(q)